Cat's claw is a woody vine native to the Amazon rainforest and other tropical areas of South and Central America. It has been used as birth control, an anti-inflammatory, an immune enhancer, a cancer remedy, and an antiviral.

Many plant species are marketed under the name cat's claw, the most common being Uncaria tomentosa and Uncaria guianensis. Both are used to treat the same conditions, although Uncaria tomentosa is thought to be more effective.

There are reports that a possibly toxic plant, Acacia greggii, has replaced cat's claw in some commercial formulas. Cat's claw may be contaminated with other Uncaria species, some that may lower blood pressure, slow heart rate, or affect the nervous system.

Cat's claw has been studied as medicine for many conditions, including osteoarthritis and rheumatoid arthritis. While results have been promising, evidence is still lacking.

These uses have been tested in humans or animals. Safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider.

GRADE *

At this time, evidence is lacking in support of the use of cat's claw for any allergic condition. More research is needed in this area.

C

Early study suggests that cat's claw may reduce inflammation. Cat's claw has been found to improve arthritis pain; however, effects on overall stiffness and swelling were lacking. One study reported an extract of cat's claw to be safe and effective for people with rheumatoid arthritis who were taking prescription drugs. Cat's claw may also reduce pain from knee osteoarthritis. More research is needed before further conclusions can be made.

C

A trial reports that a combination Chinese product containing cat's claw may help improve circulation and reduce swelling. However, more research is needed to understand the potential effects of cat's claw alone.

C

Early study has found promising evidence that cat's claw may have anticancer benefits, especially in smokers. However, high-quality trials are needed before a firm conclusion may be made.

C

Early studies suggest that cat's claw may help lower blood pressure. However, results are conflicting. More evidence is needed before cat's claw may be considered effective for this purpose.

C

Cat's claw may boost immune function in people who have HIV. However, there have been mixed results. More evidence is needed before the use of cat's claw may be supported for immune effects.

C

Studies suggest that cat's claw may reduce inflammation. Research has been conducted on the possible benefit of cat's claw for conditions such as rheumatoid arthritis. Further study is needed.

C

Cat's claw may have benefits in treating tooth disease. More high-quality research is needed before firm conclusions can be made.

C

* Key to grades

A: Strong scientific evidence for this useB: Good scientific evidence for this useC: Unclear scientific evidence for this useD: Fair scientific evidence for this use (it may not work)F: Strong scientific evidence against this use (it likley does not work)

Tradition / Theory
The below uses are based on tradition, scientific theories, or limited research. They often have not been thoroughly tested in humans, and safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider. There may be other proposed uses that are not listed below.

Traditionally, cat's claw has been by mouth as a tea, capsule, decoction, extract, or tincture.

To treat arthritis, 100 milligrams of a freeze-dried aqueous cat's claw extract has been taken by mouth daily. Krallendorn® capsules (containing 20 milligrams of radix Uncariae tomentosae) has been taken by mouth three times daily. Vincaria® has been taken by mouth as 100 milligrams daily for four weeks. A dose of 60 milligrams of Uncaria tomentosa extract has been taken by mouth daily for 24-52 weeks. Six cat's claw (Uncaria tomentosa) capsules (Primal Nature Products) have been taken by mouth daily for six months. An extract of 100 milligrams of Uncaria guianensis has been taken by mouth daily for four weeks.

As a cancer treatment, 6.5 grams of dried cat's claw bark has been boiled in water for three hours and taken by mouth for 15 days.

To stimulate the immune system, 250-350 milligrams of C-Med-100® (an aqueous extract of cat's claw) has been taken by mouth 1-2 times daily for 6-8 weeks.

Children (under 18 years old)

There is no proven safe or effective dose for cat's claw in children.

Safety
The U.S. Food and Drug Administration does not strictly regulate herbs and supplements. There is no guarantee of strength, purity or safety of products, and effects may vary. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare provider before starting a new therapy. Consult a healthcare provider immediately if you experience side effects.

Allergies

Avoid in people with a known allergy or sensitivity to cat's claw, members of the plant family Rubiaceae, or any species of Uncaria, including Uncaria rhynchophylla, which is used in Chinese herbal preparations under the name Gou-Teng.

Side Effects and Warnings

Cat's claw is possibly safe when taken in recommended doses. A freeze-dried aqueous extract of Uncaria guianensis may be safe when taken by mouth for up to four weeks. Extracts of Uncaria tomentosa, free of tetracyclic oxindole alkaloids, may be safe when taken by mouth for up to 24 weeks.

Use cautiously in people who have kidney problems or those taking agents that may harm the kidneys. Cat's claw may cause kidney failure.

Cat's claw may increase the risk of bleeding. Caution is advised in people with bleeding disorders or taking drugs that may increase the risk of bleeding. Dosing adjustments may be necessary.

Cat claw's may cause low blood pressure. Caution is advised in people taking drugs or herbs and supplements that lower blood pressure.

Use cautiously in people who have heart disorders or are taking drugs for heart disorders. Cat's claw may cause abnormal heart rhythms.

Cat's claw may interfere with the way the body processes certain drugs, herbs, or supplements using the liver's "cytochrome P450" enzyme system.

Use cautiously in people taking antioxidants.

Use cautiously in children due to a lack of safety data.

Use cautiously in people who have hormonal disorders. Cat's claw may affect levels of hormones.

Use cautiously in people who have stomach disorders. Cat's claw may cause changes in bowel movements, diarrhea, nausea, and stomach pain.

Use cautiously in people who have dizziness. Cat's claw may cause dizziness.

Use cautiously in people taking agents that may affect nervous system function (anticholinergics), anti-inflammatory agents, or pain relievers. Cat's claw may interact with these agents.

Avoid in pregnant women due to safety concerns. Cat's claw may cause abortion.

Avoid in people who have autoimmune diseases such as lupus or multiple sclerosis (MS), or those taking agents that affect the immune system. Cat's claw may affect the immune system.

Avoid in people with a known allergy or sensitivity to cat's claw, members of the plant family Rubiaceae, or any species of Uncaria, including Uncaria rhynchophylla, which is used in Chinese herbal preparations under the name Gou-Teng.

Avoid in people who are taking agents that may treat retrovirus infections, such as protease inhibitors and non-nucleoside reverse transcriptase inhibitors (NNRTIs). Cat's claw may interact with these drugs.

Cat's claw may increase the risk of bleeding when taken with drugs that increase the risk of bleeding. Some examples include aspirin, anticoagulants ("blood thinners") such as warfarin (Coumadin®) or heparin, anti-platelet drugs such as clopidogrel (Plavix®), and non-steroidal anti-inflammatory drugs such as ibuprofen (Motrin®, Advil®) or naproxen (Naprosyn®, Aleve®).

Cat's claw may interfere with the way the body processes certain drugs using the liver's "cytochrome P450" enzyme system. As a result, the levels of these drugs may be increased in the blood, and may cause increased effects or potentially serious adverse reactions. People using any medications should check the package insert, and speak with a qualified healthcare professional, including a pharmacist, about possible interactions.

Cat's claw may increase the risk of bleeding when taken with herbs and supplements that are believed to increase the risk of bleeding. Multiple cases of bleeding have been reported with the use of Ginkgo biloba, and fewer cases with garlic and saw palmetto. Numerous other agents may theoretically increase the risk of bleeding, although this has not been proven in most cases.

Cat's claw may interfere with the way the body processes certain herbs or supplements using the liver's "cytochrome P450" enzyme system. As a result, the levels of other herbs or supplements may become too high in the blood. It may also alter the effects that other herbs or supplements possibly have on the P450 system.

Cat's claw may cause low blood pressure. Caution is advised in people taking herbs or supplements that lower blood pressure.

Cat's claw may also interact with anesthetics, antibacterials, anticancer herbs and supplements, antigout herbs and supplements, antihistamines, anti-inflammatory herbs and supplements, antioxidants, antivirals, birth control, cholesterol-lowering herbs and supplements, herbs and supplements that may affect blood vessel width, herbs and supplements that may affect heart rate, herbs and supplements that may affect the immune system, herbs and supplements that may affect nervous system function (anticholinergics), herbs and supplements that may harm the kidneys, herbs and supplements that may promote urination, herbs and supplements that may treat abnormal heart rhythms, herbs and supplements that may treat arthritis, herbs and supplements that may treat Parkinson's disease, herbs and supplements that may treat nervous system disorders, herbs and supplements that may treat seizure, herbs and supplements that may treat stomach disorders, hormonal herbs and supplements, iron, maca, and pain relievers.

The information in this monograph is intended for informational purposes only, and is meant to help users better understand health concerns. Information is based on review of scientific research data, historical practice patterns, and clinical experience. This information should not be interpreted as specific medical advice. Users should consult with a qualified healthcare provider for specific questions regarding therapies, diagnosis and/or health conditions, prior to making therapeutic decisions.